import java.util.concurrent.Semaphore;

public class Demo2 {
    static int a = 0;
    public static void main(String[] args) throws InterruptedException {
        Semaphore semaphore = new Semaphore(1);
        Thread t1 = new Thread(() -> {
            try {
                semaphore.acquire();
                for (int i = 0; i < 5000; i++) {
                    a++;
                }
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
            semaphore.release();
        });
        Thread t2 = new Thread(() -> {
            try {
                semaphore.acquire();
                for (int i = 0; i < 5000; i++) {
                    a++;
                }
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
            semaphore.release();
        });
        t1.start();
        t2.start();
        t1.join();
        t2.join();
        System.out.println(a);
    }
}
